Inertia actuated magnetic fuze firing pin



' l Feb. 24,. E948.

J. F'. MccAsLlN INERTIA AGTUATED MAGNETIC FuzEl FIRING PIN v Fiied March 6, 19454 l I I I T.

Y. Patented Feb. 24, 1948 Pf i @E F fCfE INERTIzr-ACTUATED M-AGNE'r-re-*Fczn HIRING PIN Thisinventiom relates ,td an. improyed" ring 5,.,

pin for projectile fuzes, ,andfmoreparticularlyttd uzesbthe inertiaactuatedltvpe which. are .norrnally.A held in a ,re,tr.acted nositionby. alcreep, spring onshearpinm The.. principal disadvantage. ofV employing a. i,

cree-p lspringgicr.: holding the ring pinL or, striker; of, aniinertia actuated. proiectilejfuze. inl a l re-, tracted'position, resides, in., the, fact.` that the re: sistancefto.the` forward movement of .the tiring pini.

under, the.impulselinertia, when the projece lltile strikes a target, ,isincreased as A.the `i'ring. pin approaches the. percussion.. cap or. detonator. As aresu1t,a... glancing .hitfrequently results, in the, fuse failing. to function Also, the crce .of,the.v

spring,r.equired" to,V overcome creep, is so .slight 20.

that, a. ,springofsuch resistanceis too sensitivet so that suchlsprings: arennade much.. stronger.. thus requiring greater inertia force to overcome their resistance... In` fuzes of.` thetype, ernnlcying al shearwire. or, -pinifon holding the, ringgpnn until. actuated'by inertia upon.impact Y,ofthe prio.- jectilewith a,target,.it iscustomary to space-the nitingpinjromthe,rear end 'of the fiiz'ehousing or. barrelY in, which the iringV pin slidablyjj:

videmeans forholdingfaifiring pin in a retracted: position-which .will function to return the ring; pin toafullyretracted position should it .be moved. slightly.. toward .a .projected position.

More. particularly,.ity is vanairn ofthe inven tiomtoprovidefa magneticmeans for holding the.. ring.pinninlaretracted positionY and which will? retardtheini-tial forward movement of the firing: pinlunderinertia,impetus, until the travel of thel ringpinisfsufcient to. produce an airgap hay ing. a. value at which.. the magnetic field is` nc,A longer capableofovercoming the inertia force, to.I therebyproduce aA sudden rupturing. of theA mag.- netidfleid-landi-a sudden. breakaway or snap aC-.` tion releasev of, the. firing pin to. allow a1 iinal; unretarded'movement ofthe. firing pinv to tha peicussicmz-cap,.v

Qtherobjectsand advantages of the invention. willhereinafter4 become more fully apparent .from ,v the follcwingdescriptionfof the drawing, which... illustrates preferred embodiments thereof; and,

whereirirl,

Figure; isa fragmentary longitudinal sec-,- tional View, partly in elevatiomf aportion. of .aff riea grenade.. shown equipped with the` improved fuze;

Y Eigure. 2 is' cross sectional view of the fuzev taken substantiallyalong aplane. as indicatedby,A Unete-2 .otligure- 41;.

mounted, solthatjslightirregularitiesin thesize- Eigure: 3:.. is:` a. fragmentary longitudinal sec:

of the parts,l will" not prevent. the* application. of the shear wire or pin, and consequently,v the shearwire or p in is frequently sheared'orweakcned. hy setback` force uponacceleration ofA the;Y

projectile; to thereby` destroygorminimlze its "utils ;vr

ity as .a safetyk factor and toirequently restrictif.,`L premature. detonation; oftlieproje'ctile:

The primary object of :the present invention to providean improved construction'of uze-tli-atpermits.asuddenbreakawayof thering pinfrom` 4d.

proaohes the percussioncap, sev that detonation= H of the prol`ctii1ewillbefinsured;evexrzon` glancing hits.

Ancther object of the invention is te providea constructiorrwhereinl the-setback force occurring during accelerationn will not 4aect the function- 517 ing of the sudden breakaway retarding means, due to the fact that said means retains the ring pin against the rear end of the housing or barrel in which the pin is movably mounted. A

tion-alview, partlyin elevation, of. a slightly modiedform,efthe fuze; and

Eigu-re 'Lisafragmentary longitudinal sectionalview, ci; a.. slight fmodication of the fune, of Fig-,- 11H-171;. Y

Referring more, particularly tc -the drawing, whereinilike referencecharacters designate. like. or corresponding.V parts throughout the several. views, in Eigures l, 2 and/L5 designates generally; asportiorrofta ,rifle grenade shown merely to.i11us, trategone appli-cation of, theimnroyedfuze, desig natedlgenerally andtccmprlsing the. invention.'` Y The-fuse Rincludes a.substantially cylindricaL housing `l' hamng areduced neck at its forwardK ende which, is.,exte1naily. threaded to., engagetha internally threadedcollar 9, forming therear end` cffthegienadelheadoe bur-ster. chamber lll. The housing lvis:providedV withalongitudinally exe tending bol-re" l-l the forward end I 2 of. .whichis enlarged and internally threaded and opens'into the head lll. The rear end of the bore Il is closed, either by the rear end of housing 1 being solid as shown in Figures 1 and 2, or by means of a plug I3 which may be threaded or otherwise Still a further aim of the invention is to prosecured in housing l', as illustrated in Figure 4.

The plug I3 is formed of a magnetic material such as iron or soit steel and the remainder of the housing l', of Figure 4, is preferably formed of a nonmagnetic material, such as brass, for a `purpose which will hereinafter become apparent,

contact with the booster I5.at its forward end. Y`

Holder Id is also provided with a centrally disposed' opening I1 in its rear end which communicates with the percussion cap I6.

A ring pin I8 is slidably mounted in the bore II and includes a piston-shaped body portion I9 having an annular groove 20 therein through which a removable safety pin or wire 2l extends and which is anchored in the housing l, for providing a positive safety means to hold the firing Y pin I8 in a retracted position, in the rear end of the bore I I and away from the percussion cap I6. The firing pin I8 is provided with a tapered pointed projection 22 at its forward end, forming the point of the firing pin and which is disposed to pass through the opening I1, onV forward movement of the firing pin I8, to strike and detonate the percussion cap I6. A horseshoe type magnet 23 is secured in the rear end of the body I9 as by means of the dove tail joint, as shown, and projects rearwardly therefrom. .The two legs of the magnet 23, which are of opposite polarity, are disposed to normally engage the rear end of housing l' or the insert I3 and as said portions are attracted by the magnet 23 and are in a fixed position, said magnet 23 functions to retain itself and the firing pin I8 at the rearmost position of the firing pin in the bore II, as illustrated in Figure 1.

From the foregoing, it will be obvious that after the safety pin 2l has been removed to arm the fuze G, that upon impact of the rie grenade with a target the force of inertia will cause the firing pin I8 to be urged forward thereby and against the magnetic pull produced by the magnet 23 on the rear end of housing 'I or the insert I3. As the firing pin I8 is moved forward under this impetus of inertia, the pull created thereby will overcome the force of the magnetic eld of the magnet 23, thereby rupturing this field and releasing the firing pin, to permit its unret'arded movement from there to the primer IB, to detonate the primer, the booster I5 and the charge of high explosive contained in the head I0. By forming the housing 'I' of a nonmagnetic material, as shown in Figure 4, there is vno possible tendency of the magnet to exert a pull on any other portion of the housing 1', except the insert I3, so that once the initial magnetic eld is ruptured the travel of the firing pin vI8 to the primer I8 is positively unretarded.

In Figure 8 a slightly modified form of the fuze, designated generally 24, is shown, which differs from thefuze 6 in that a horseshoe type magnet 25 is anchored in a socket 26, in the rear end of the fuze housing 21, and has its legs projecting into the bore 28. The ring pin 29 differs from the firing pin I8 only in that the magnet is omitted therefrom and at least its rear portion 30 is formed of a magnetic material, such as iron or soft steel, which is attracted by the magnet 25 for normally holding the firing pin 29 in a retracted position, away from the primer I6 and at the rear end of the bore 28. The functioning of the firing pin 29, after removal of its safety wire or pin, is identical with that of the firing pin I8, in that as the ring pin is moved forward by inertia the magnetic iield of magnet 25 will be suddenly ruptured to release the firing pin 291, to permit its unretarded travel thereafter to the percussion cap.

If required to provide additional magnetic force, a magnet could be mounted in the firing pin, as shown in Figure 1, and also in the rear of the fuze housing, as illustrated in Figure 3, so that when the magnets were arranged with their poles to attract, the retarding force on the ring pin would be doubled.

The ring pin I8 may be formed of aluminum or other light alloy, if desired.

Obviously, the invention, which is hereinafter defined by the appended claims, is capable of use with any type of projectile fuze which is inertia actuated, such as rocket projectiles and artillery projectiles, and aerial bombs and has been illustrated and described in conjunction with a rifle grenade, merely for the purpose of illustrating one use of the fuze and should not be construed as a limitation upon the wide variety of uses for which the fuze is adapted.

Likewise, various other modifications and changes in the construction and arrangement of the fuze parts are contemplated and may obviously be resorted to, Without departing from the spirit and scope of the invention, as hereinafter defined by the appended claim.

I claim:

A projectile fuze comprising a housing of nonmagnetic material, a primer charge disposed at the forward end of the said housing, the rearward end of said housing having an opening, a plug of magnetic material secured in said opening, a firing pin slidably engaged within the said housing and a permanent magnet secured to the said firing pin and engageable with said plug whereby said ring pin is held by magnetic at' REFERENCES CITED The following references areof record in the le of this patent: v

UNITED STATES PATENTS Number Name Date 384,662 Zalinski June 19, 1888 1,197,729 Flather Sept. 12, 1916 

